Fireproofing and creaseproofing of cellulose and protein textiles



Patented Nov. 14, 1950 FIBEPROOFING AND CREASEPROOFING OI CELLULOSE. AND PROTEIN TEXTILES Thomas H. Morton and Frank Ward, Braintree,

England, assignors to Courtaulds Limited, London, England, a British company No Drawing. Application November 27, 1948, Segial No. 62,408. In Great Britain August 22,

8 Claims. 1

This invention relates to a process for the treatment of cellulosic and protein textile materials, including fibres, yarns and fabrics to improve certain of their properties, for example their crease-resistance and their fire-resistance.

It is known to fireproof textile materials by impregnating them with solutions of nitrogenous compounds; for example in the specification of British Letters Patent No. 476,043 solid combustible substances are treated with a condensation product which has been made by condensing dicyanodiamide with aldehydes. The said specification states that the solution obtained by treating with formaldehyde the mother or washing liquors from the production of dicyanodiamide from cyanamide or calcium cyanamide may be used to carry out the process, and that other combustion-retarding substances may be applied to the combustible substances at the same time, e. g. phosphoric acid, boric acid, hydrobromic acid, or salts thereof. According to the specification of British Letters Patent No. 490,542 transparent homogeneous sheet materials made of organic hydrophilic colloids are fireproofed by incorporating in the transparent material a water-soluble salt of an aliphatic organic nitrogen base with an acid of phosphorus. According to the specification of United States Letters Patent No. 2,212,152 organic combustible materials, particularly textile and cellulosic materials, are fiameproofed by applying as a fire-retardant a fusion product of urea and sulphamic acid. According to the specification of United States Letters Patent No. 2,418,525 textiles and fabrics are rendered permanently not inflammable, water-resistant and mildewproof, by passing the materials through aqueous solutions containing pyrophosphoric acid and melamine, precipitating thereby on and within the fibres of the treated article finely divided melamine pyrophosphate and insolubilizing the latter on the fibre by drying the articles at a temperature of about between 120 to 140 centigrade. The melamine pyrophosphate is precipitated on the fibre, but does not apparently react with the fibre. According to the specification of British application No. 4201/45 Ser. No. 604,197 as laid open to public inspection cellulosic and protein textile materials are fiameproofed by impregnating the fabric with phosphoric acid and urea and subjecting to a curing temperature of not less than 270 Fahrenheit for a time sufiicient to effect the cure (i. e. combination of the phosphoric acid and urea with the material of the fabric) but insufiicient to objectionably tender and weaken the fabric. According to the specification of British Application No. 22,178/45 as laid open to public inspection cellulosic and protein materials are fiame-proofed by applying an aqueous solution comprising one or more acids of the group consisting of phosphoric, sulphuric, sulphamic and phosphamic acids, one or more of the nitrogen containing compounds of the group consisting of urea, biuret, dicyandiamide, aminoguanidine carbonate and guanidine, one or more of the aldehydes of the group consisting of formaldehyde, glyoxal, chloral hydrate, acetaldehyde, acrolein and aldol, and one or more of the alkaline agents of the group consisting of ammonium hydroxide, ethylene diamine, diethylamine, trimethylamine and triethylamine and heating at 250 to 400 Fahrenheit for from 2 hours to 30 seconds. None of these prior proposals mentions the use of cyanamide for fireproofing textile materials.

It is also known to treat textile materials with condensation products of cyanamide and formaldehyde; for example in the specification of United States Letters Patent No. 2,234,905 it has been proposed to improve the dyeing properties of textile materials by incorporating in the materials a product obtained by causing cyanamide and formaldehyde to react under acid or neutral conditions. The specification states that the impregnating solution is obtained by mixing, in the cold, solutions of cyanamide and formaldehyde, that the solution is maintained slightly acid, and that reaction between the cyanamide and formaldehyde is effected by heating after the solution has been applied to the material and the material has been dried, The best results are said to be-obtained when the pH value of the solution lies between 5.0 and 6.5. According to the specification of United States Letters Patent No. 2,253,457 the dyeing properties of textile materials are improved by treating them before or after dyeing with a solution obtained by dissolving in acid the product which is produced by the interaction of cyanamide and formaldehyde.

- The compound of cyanamide and formaldehyde may be dissolved in dilute sulphuric acid. Ac-

cording to the specification of United States Letters Patent No. 2,247,353 textiles are sized to render them crushproof and creaseproof by impregnating the textile materials with an aqueous solution of cyanamide, prepared of a concentrated cyanamide solution, having a concentration of 6 to 7 per cent of cyanamide, and a formaldehyde solution of 40 per cent strength, in proportions of parts by weight of 1.86 to 4.16

ters Patents No. 2,234,905 and No. 2,247,353 the acid is present as a condensing agent. whereas in the specification of United Staes Letters Patent No. 2 253,457 the acid is used as solvent but the acid is not used to react with the textile material in any of these prior proposals.

An object of the invention is to produce cellulosic and protein textile materials containing chemically combined strong mineral acid and cyanamide.

Another obiect of the invention is to provide cellulosic and protein textile materials having improved fire-resistance, crease-resistance and other properties.

A further object of the invention is to provide cellulosic and protein textile materials which are fire-resistant and free from after-glow.

A further object of the invention is to provide cellulosic and protein textile materials having improved properties which are fast to water and to light soaping.

A further object of the invention is to provide an impregnating solution containing strong mineral acid which can be used for the treatment of cellulosic and protein textile materials without causing undue tendering of the cellulose or protein.

These and other objects are accomplished by providing cellulosic and protein textile materials containing chemically combined stron mineral acid and cyanamide, the quantity of combined acid being at least 1 per cent by weight based on the weight of the materials. In addition, the cellulosic and protein textile materials containing at least 1 per cent by weight of combined acid based on the weight of the materials preferably contain at least 3 per cent by weight of combined acid and cyanamide.

Cellulosic and protein textile materials are impregnated with an aqueous solution containing a non-volatile strong mineral acid and cyanamide and chemical combination is effected between the textile materials, the acid and cyanam de by drying and baking the impregnated materials so as to obtain cellulosic and protein textile materials containing at least 11 per cent -by weight based on the weight of the materials of combined mineral acid. The final product also preferably contains a total of at least 3 per cent by weight of the combined mineral acid and cyanamide together based on the weight of the materials.

The non-volatile strong mineral acids which may be used in carrying out the process of the present invention include the following:

Orthophosphoric acid. H3PO4 Phosphorous acid, H3PO3 Pyrophosphoric acid, HiPzOv Phosphamic acid, NHzHzPOa Sulphuric acid, H2804 Sulphamic acid, NH2.HSO3

A mixture of mineral acids may be used. The acid may be partly neutralised by an inorganic base for example ammonia, caustic soda or caustic potash or by an organic base for example monoethanolamine, provided that the resulting salt is sufflciently soluble in water, the limit of neutralisation being the mono-substituted salt in the case of the orthophosphoric acid.

The ratio of mineral acid to cyanamlde in the impregnating solution preferably lies between 1:3 and 2: 1.

Formaldehyde may be present in the impre nating solution and may be added wholly or part ly in the form of hexamethylene tetramine or may be added as formaline (a 35 per cent aqueous solution of formaldehyde). Formaline is preferably present in not more than 1.5 times the amount of mineral acid plus cyanamide.

The textile fibres or yarns are impregnated in any suitable manner, for example, by immersion in the aqueous solution followed by centrifuging or mangling to remove excess solution, or by spraying the aqueous solution on to the fibres or yarns. The textile fabrics may be impregnated by immersion in the aqueous solution or by treatment on a padding machine.

After impregnation of the fibresyarns or fabrics excess of the solution is removed and the fibres, yarns or fabrics are dried. preferably at 50 to centigrade. The dried fibres, yarns or fabrics are then baked to eifect the reaction between the cellulose (or protein). the mineral acid and the cyahamide. The conditions of time and temperature to effect the reaction can be ascertained by a practical test; the mildest conditions of shortest time and lowest temperature consistent with the completion of the chemical reaction will be chosen in order to avoid undue tendering of the textile fibres, yarns or fabrics. Suitable conditions of baking are heating at temperatures of to centigrade for a period of from 5 minutes to 1 hour, although the heating may be carried out at temperatures lower or higher than this range, for example, heating at 80 centigrade for 10 minutes or heating at centigrade for 5 minutes.

After baking, the textile fibres, yarns or fabrics are treated to stabilise and neutralise the material by washing in running hard water or in running soft water which contains 0.05 per cent of sodium bicarbonate formed during the softening process or by treating in a bath of dilute sodium carbonate solution.

The process of the present invention is applicable to cellulosic textile fibres, yarns or fabrics, for example cotton or regenerated cellulose such as viscose rayon continuous filament yarn or viscose rayon staple. When treating regenerated cellulose textile fibres, yarns or fabrics the process may be applied at any stage of manufacture after drying, for example it may be applied to the tow of dried continuous filaments prior to the cutting operation or to the dried out fibres; it is preferably applied to the fabric directly after dyeing. The process is particularly valuable for the treatment of fabrics from viscose rayon staple. The process of the present invention is also applicable to protein fibres, for exam le. silk, wo l or artificial fib s from casein.

In carrying'out the process of the present invention a definite chemical combination takes place between the cellulose (or protein), the acid and the cyanamide. The reaction takes place throughout the body of the material, that is substantially within the individual fibres or individual filaments of the yarn or fabric.

The cellulosic (or proten) textile fibres, yarns or fabrics treated according to the process of the present invention contain combined nitrogen and either combined phosphorus or sulphur depending on the mineral acid used in the impregnating solution. The treated materials have improved properties which are fast to water and to light soaping. The improvements in the properties of the treated fibre, yarn or fabric depends on the conditions of the treatment and on thetype of mineral acid used in the impregnating solution. For example, a fabric treated according to the process of the present invention in an impregnating solution containing to 40 per cent of phosphoric acid and 8 to 25 per cent of cyanamide, possesses improved crease-resistance, fire-resistance and a low water-imbibition, whereas a fabric treated in an impregnating solution containing 10 to 20 per cent of sulphuric orthophosphoric acid and cyanamide give a fab ric with improved crease-resistance but without any substantial improvement in fire-resistance. The addition of formaldehyde to the impregnating solution inhibits tendering of the fabric and gives a better colour than a fabric treated without the addition of formaldehyde. Neutralisation of part of the acid in the impregnating solution improved the stability of the impregnating solution and reduces tendering of the fabric.

The textile fibres treated according to the present invention. are fire-resistant and may be used for the production of fabric which have good fireresistant properties. The process is particularly useful for the treatment of viscose rayon staple which is to be used for the production of pile yarns for carpets.

The following examples will illustrate the process of the present invention:

Example 1 A fabric made from viscose rayon staple was impregnated with a solution containing 20 per cent of orthophosph'oric acid and 24 per cent of cyanamide. The fabric was mangled, dried at 50 to 80 centigrade and then heated for '7 minutes at 105 centigrade. The fabric was stabilised by washing in running hard water for two hours and was dried on a frame. The fabric was found to have a combined nitrogen content of 5.5 per cent and a combined phosphoric acid content of 9.6 per cent. The treated fabric was fire-resistant, crease-resistant and had a low water-imbibition.

Example 2 A fabric made from viscose rayon staple was impregnated on a padding machine with a solution containing 10 per cent of orthophosphoric acid, 7.5 per cent of ammonium dihydrogen phosphate and 21 per cent of cyanamide. The fabric was mangled, dried at 50 to 80 centigrade and then heated for minutes at 140 centigrade. The fabric was stabilised as in Example 1. The fabric was crease-resistant, fire-resistant and had a low water-imbibition. The fabric was found to have a combined nitrogen content of 4.2 per cent and a combined phosphoric acid content of 9.1. per cent.

. Example 3 A fabric made from viscose rayon staple was impregnated on a padding machine with a solution containing 12 per cent sulphuric acid, 8 percent of ammonium sulphate and 21 per cent of cyanamide. The fabric was mangled, dried at 50 to 80 centigrade and heated for 7 minutes at 140 centigrade. The fabric was stabilised by washing for 2 hours in running softened water containing 0.05 per cent of sodium bicarbonate formed during the softening, and dried on a frame. The fabric was found to have a combined nitrogen content of 4.1 per cent and a combined sulphuric acid content of 15.8 per cent. The treated fabric was fire-resistant and this eifect was found to persist after treatment with hot dilute alkali.

Example 4 A fabric made from viscose rayon staple was impregnated on a padding machine with a solution containing 9 per cent of orthophosphoric acid, 5 per cent of sulphuric acid and 24 per cent of cyanamide. The fabric was mangled, dried at 50 to 80 centigrade and heated at 140 centigrade for 5 minutes. The fabric was stabilised as described in Example 3. The fabric was fire-- resistant and crease-resistant. The treated fabric was found to have a combined nitrogen content of 3.4 per cent, combinedphosphoric acid content of 5.2 per cent and a combined sulphuric acid content of 6.0 per cent.

Example 5 A fabric made from viscose rayon staple was impregnated on a padding machine with a solution containing 20 per cent of phosphoric acid, 16 per cent of cyanamide and 2'7 per cent of a per cent solution of formaldehyde. The fabric was mangled, dried at to centigrade and heated for 5 minutes at 140 centigrade. The fabric was stabilised by washing for 2 hours in water containing 0.1 gram per litre of sodium carbonate. The treated fabric was fire-resistant and crease-resistant. The fabric was found to have a combined nitrogen content of 8.2 per cent and a combined phosphoric acid content of 9.6 per cent.

Example 6 Viscose rayon staple was impregnated with an aqueous solution containing 7 per cent of sulphuric acid, 4 per cent of sodium bisulphate and 18 per cent of cyanamide. The rayon staple was hydroextracted so that the increase in weight was approximately per cent, dried at 50 to 80 centigrade and baked for 2 minutes at centigrade to effect reaction between the cellulose, the sulphuric acid and the cyanamide. The treated rayon staple was washed in soft water containing a small quantity of sodium carbonate to make it slightly alkaline and finally dried. The rayon staple was found to have a combined sulphuric acid content of 9.5 per cent and a combined nitrogen content of 1.9 per cent. The treated rayon staple was fire-resistant.

Example 7 Viscose rayon tow which had been washed and dried was impregnatedwith an aqueous solution containing 6 per cent of sulphuric acid, 8 per cent of ammonium dihydrogen phosphate and 18 per cent of cyanamide and mangled so that approximately 100 per cent of the treating solution was retained in the tow. The tow was dried at a temperature below 70 centigrade, baked for 1 minute at centigrade and washed in running soft water for 2 hours and finally dried.

The tow was found to have a combined nitrogen content of 1.8 per cent, a combined sulphuric acid content of 5.5 per cent and a combined phosphoric acid content of 4.8 per cent. The tow was found to be fire-resistant. The tow was converted to a rayon staple yarn which was made 7 into a fabric. The fabric obtained was fire-resistant and free from after-glow.

Example 8 A 100 per cent woollen fabric was impregnated on a padding machine with an aqueous solution containing 10 per cent of sodium bisulphate, 7 /2 per cent of sulphuric acid and 18 per cent of cyanamide. The fabric was hydro-extracted dried below 70 centigrade and heated at 140 centigrade for 5 minutes. The fabric was stabilised by washing for 2 hours in watercontaining 0.1 gram per litre of sodium carbonate. The fabric was fire-resistant and this efiect was found to persist after soaping. The fabric was also more resistant to alkaline treatments than untreated woollen fabric.

Example .9

A cotton fabric was impregnated on 9. padding machine with an aqueous solution containing 12 per cent of sulphamic acid, 12 per cent of phosphoric acid having a specific gravity of 1.75, 4 per cent of sodium bisulphate and 24 per cent of cyanamide. The fabric was mangled, dried at between 50 and 80 centigrade and baked at 140 centigrade for 3 minutes. The fabric was stabilised by washing in water containing a small quantity of sodium carbonate and dried on a frame. The fabric was fire-resistant and free from after-glow; this effect persisted after light soaping.

Example A cotton fabric was mercerised for 1 minute in 45 Twaddell caustic soda, washed whilst maintaining the fabric dimension, and finally soured in dilute sulphuric acid to destroy any remaining alkali. After squeezing and whilst the fabric was still in the wet condition it was treated in an aqueous solution containing 7 per cent of sulphuric acid, 12 per cent of sodium bisulphate and 18 per cent of cyanamide. The fabric was mangled, dried below 80 centigrade and baked at 105 centigrade for 5 minutes. The fabric was stabilised by washing for several minutes in a dilute aqueous sodium carbonate solution containing approximately 0.1 gram of sodium carbonate per litre. The treated fabric was found to contain 13 per cent of combined sulphuric acid and 2.2 per cent of combined nitrogen. The

fabric was fire-resistant and the eifect persisted after light soaping.

What we claim is:

1. Cellulose and protein textile materials having within the individual fibers at least 3 per cent by weight of chemically combined non-volatile strong mineral acid and cyanamide produced by impregnating said materials with an aqueous solution consisting of 5 to 40 per cent of a non-volatile strong mineral acid and 8 to 25 per cent of cyanamide, drying at a temperature of below 80 centigrade and baking at a temperature of from 80 to 160 centigrade.

2. A process for improving the properties of cellulose and protein textile materials which comprises impregnating said materials with an aqueous solution consisting of from 5 to 40 per cent of a non-volatile strong mineral acid and from 8 to 25 per cent of cyanamide, drying at a temperature of below 80 centigrade and baking at a temperature of from 80 to 160 centigrade so as to obtain cellulose and protein textile materials containing at least 3 per cent by weight based on the weight of the materials of chemically combined non-volatile strong mineral acid and cyanamide distributed within the individual fibers of the material.

3. A process as claimed in claim 2 in which the ratio of acid to cyanamide in the impregnating solution lies between 1:3 and 2:1.

4. A process as claimed in claim 2 in which the acid in the impregnating solution is in part neutralized by a base to give a water-soluble salt.

5. A process as claimed in claim 2 in which a mixture of non-volatile strong mineral acids is used in the impregnating solution.

6. A process for improving the properties of cellulose and protein textile materials which comprises impregnating said materials with an aqueous solution consisting of from 5 to 40 per cent of a non-volatile strong mineral acid, from 8 to 25 per cent of cyanamide and a 35 per cent formaldehyde solution in an amount equal to not more than 1.5 times the combined total weight of the acid and cyanamide, drying at a temperature of below centigrade, baking at a temperature of from 80 to centigrade so as to obtain cellulose and protein textile materials containing at least 3 per cent by weight based on the weight of the materials of chemically combined non-volatile strong mineral acid and cyanamide distributed within the individual fibers of the material and finally washing and drying the materials.

7. A process for improving the properties of cellulose and protein textile materials which comprises impregnating the materials with an aqueous solution consisting of from 5 to 40 per cent of a non-volatile strong mineral acid selected from the group consisting of Orthophosphoric acid, H3PO4 Phosphorous acid, HaPOa Pyrophosphoric acid, H4P207 Phosphamic acid, NHzHzPO: Sulphuric acid, H2804, and Sulphamic acid, NHzHSOs and from 8 to 25 per cent of cyanamide drying at a temperature of below 80 centigrade, baking at 8. Cellulose and protein textile materials having within the individual fibers at least 3 per cent by weight of chemically combined non-volatile strong mineral acid and cyanamide produced by impregnating said materials with an aqueous solution consisting of 5 to 40 per cent of a nonvolatile strong mineral acid selected from the group consisting of Orthophosphoric acid, H3P04 Phosphorous acid; HsPOa Pyrophosphoric acid, H4P2O': Phosphamic acid, NHzHzPOa Sulphuric acid, E304, and Sulphamic acid, NHzHSOa and 8 to 25 per cent of cyanamide, drying at a temperature of below 80 centigrade and baking at a temperature of from 80 centigrade to 160 centigrade.

T. H. MORTON. F. WARD.

(References on following page) REFERENCES CITED Number The following references are of record in the t file of thls pa, ent 2,488,034

UNITED STATES PATENTS 5 Number I Name Date 2,089,697 Groebe Aug. 10, 1937 Number 2,234,905 Tallis Mar. 11, 1941 36;;

Name Date Auer July 1, 1941 Whittaker et a1. Aug. 19, 1941 Pingree et a1. Nov. 15, 1949 FOREIGN PATENTS Country Date Great Britain June 10, 1944 Switzerland May 16, 1938 

1. CELLULOSE AND PROTEIN TEXTILE MATERIALS HAVING WITHIN THE INDIVIDUAL FIBERS AT LEAST 3 PER CENT BY WEIGHT OF CHEMICALLY COMBINED NON-VOLATILE STRONG MINERAL ACID AND CYANAMIDE PRODUCED BY IMPREGNATING SAID MATERIALS WITH AN AQUEOUS SOLUTION CONSISTING OF 5 TO 40 PER CENT OF A NON-VOLATILE STRONG MINERAL ACID AND 8 TO 25 PER CENT OF CYANAMIDE, DRYING AT A TEMPERATURE OF BELOW 80* CENTIGRADE AND BAKING AT A TEMPERATURE OF FROM 80* TO 160* CENTIGRADE. 